OWNERS: Add link to format

Change-Id: Ibe5a9608f3c264a62a6efc57ac1c81f48e90762e
Reviewed-on: https://pigweed-review.googlesource.com/c/infra/recipes/+/211031
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Reviewed-by: Anthony DiGirolamo <tonymd@google.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/OWNERS b/OWNERS
index 9f8ed21..c9511af 100644
--- a/OWNERS
+++ b/OWNERS
@@ -1,3 +1,6 @@
+# Syntax for OWNERS files can be found at
+# https://gerrit.googlesource.com/plugins/code-owners/+/HEAD/resources/Documentation/backend-find-owners.md
+
 danikay@google.com
 mohrr@google.com
 olivernewman@google.com